Compensating turntable drive



June 3, 1941. E V, sCHNElDER 2,244,121

COMPENSAT ING TURNTABLE DRIVE Filed Feb. 17, 1941 Patented `une v3, 194iCOMPENSATING TURNTABLE DRIVE Emmor V. Schneider, Alliance, Ohio,assignor to The Alliance Manufacturing Company, Alllance, Ohio, acorporation of Ohio Application February 17, 1941, Serial No. 379,227

(Cl. 'I4- 206) 4 Claims.

` duction motors for economic reasons,

Such phonographs however, are not entirely satisfactory, due largely tothe fact that these inexpensive motors do not have sufficient power todrive the turntable at a uniform speed from [the start to the end of arecord, especially in recording, and also because they will not drivethe turntable as rapidly when recording as when reproducing a record.

It has been found that in recording upon this type of phonograph thereis a differential of approximately eighteen inch ounces to six inchounces between the start and the end of a record, resulting innoticeable variations .in both the pitch and the tempo of recordingsmade upo such phonographs.

It has also, been founcl that there is a dierence of approximately fourrevolutions per minute between the recording and the reproducing of arecord upon such phonographs.

Another objection to this type of phonograph is that the pulsations rvibrations of the motor Vare reproduced to a greater or less degree inthe record.

The present invention has for lts objects the provision of acompensating turntable drive for phonographs` which will overcome theabove mentioned objections and produce a uniform speed in recording andreproducing of records, as well as minimize the reproduction in therecord of the pulsations or vibrations of the motor.

Another object of the invention is the provision of a turntable drive inwhich the axis of the motor is substantially parallel to the plane ofthe turntable. and in which a countershaft is provided substantiallyparallel to the motor shaft, a friction wheel upon said shaft engaging afriction pulley upon the motor shaft, a second friction wheel beingslidably mounted upon said shaft and frictionally engaging theturntable, means being provided for moving said second friction Wheeltoward and from the center of the turntable -to compensate forvariations in the drag or torque upon the turntable between the startand end of a recording," or between the recording and reproducing of arecord.

Still another object of the invention is the provision of a turntabledrive of this character in which the two friction wheels are connectedtogether byrmeans of a torsion spring through which the drive iseffected, so that the pulsations or vibrations of the motor will not bereproduced in the recording or playing of a record.

A further object of the invention is to provide a turntable drive of thetype referred to in which the slidable friction wheel is movedlongitudinally upon the shaft by means of a screw thread or helical rib.

The above objects, together with others which will be apparent from `thedrawing and following description, may be attained in various ways bywhich a slidably mounted friction vwheel is moved radially relative tothe turntable to compensate for drag or torque upon the turntable, andfor the purpose of illustration a preferred embodiment of the inventionis shown in the accompanying drawing, 'in which- Figure 1 is afragmentary top plan view of the improved compensating turntable drive;

Fig. 2, a vertical sectional view taken as on the line 2-2, Figure l;and

Fig. 3, an enlarged sectional view through the two friction wheelsandassociated parts;

Similar numerals `refer to similar parts throughout the several views.

In the form of the invention shown, a portion of the usual platform of aphonograph cabinet is shown at I0 and the turntable il is rotatablymounted upon the spindle I2 carried by said platform. v

The turntable may be provided with the usual depending peripheral flangeI3 although the same is not necessary for the particular friction driveused ln this invention. l

A motor mounting plate I4 may be supported upon the platform I0 as byone or more rubber grommets I5 secured to the platform as by the screwI6 and washer Il, a spacer sleeve It or the equivalent being preferablylocated around the s'crew and interposed between the platform and thewasher ll.

Depending arms I9 may be formed upon or attached to the motor mountingplate and located through the openings 20 and2l in the platform lll.

The motor, indicated generally at 22, is suspended upon the arms I9 towhich it may be connected as by the screws 23 and the motor is A bearing26 is swedged or otherwise connected to one arm I9 of the motor mountingplate to form a bearing for the shaft 21 which is Ilout-- naled in :aidbearing and held against accidental removal as by the flange 28 whichmay be in the form of a washer located around the reduced end portion 29of the shaft and retained thereon as by the riveted head 30 formed uponthe adjacent end of the shaft.

A friction wheel 3| is fixed upon the shaft 21 adjacent to the bearing26 as by the pin 32 iocated through the hub 33 of the friction Wheel andthrough a suitable opening 34 in the shaft.

A tire 35 of rubber or the like is mounted upon the friction wheel 3land frictionally engages the pulley 25 upon the motor shaft so that thefriction wheel 3| and shaft 21 may be rotated by the motor.

A second friction wheel 36 is mounted for longitudinal movement upon theshaft 21 and is provided with a friction tire 31 frictionally engagingthe underside of the turntable Il.

This friction wheel may be threaded upon the shaft 21 in any well knownmanner and as shown the hub 38 of the friction wheel is provided with aspiral rib 39 engaging a similar groove 4U in the shaft 21.-

Outward movement of the friction wheel 36 beyond the adjacent end of theshaft 21 maybe prevented as by the washer 4| located in a peripheralgroove 42 formed in this end portion of the shaft.

A torsion spring 43'is located around the shaft 21, one end thereofbeing connected to the hub 38 of the friction wheel 36 as indicated at44 while the other end of the spring is connected to the hub 33 of thefriction wheel 3|, and to the shaft 21 as indicated at 45.

A skirt 46 may be formed upon the hub of the Wheel 36 to surround thespring 43.

In the normal position of the parts, as shown in Figs. 2 and 3, thespring 43 holds the friction wheel 36 at the outer end of the shaft 21so that the tire of said friction wheel contacts with the The devicethus compensates for changes in drag or torque upon the turntable,providing for a smooth uniform rotation of the turntable throughout theentire recording or playing of a record.

It will also be seen that since the drive is through the torsion spring43 pulsations or vibrations of the motor will be absorbed by the springproducing a smooth continuous rotation of the turntable.

I claim:

1. A transmission including a driving means, a driven disk, a shaftoperatively connected to the driving means, the axis of said shaft beinglocated in a plane parallel to the normal plane of the driven disk, afriction wheel longitudinally movable upon the shaft and frictionallyengaging the adjacent side of the driven disk. and torsion spring andscrew means connecting the friction wheel and the shaft for moving thefriction wheel toward and from the center of the driven v disk tocompensate for variations in drag and resultant speed changes of thedriven disk.

2. A transmission including a driving means, a driven disk, a shaftoperatively connected to the driving means and located radially relativeto the driven disk, a friction wheel longitudinally movable upon theshaft and frictionally engaging the adjacent side of the driven disk,and torsion spring and screw means connecting the friction wheel and theshaft for moving the friction wheel radially upon the drivendisk tocompensate for variations in drag and resultant speed changes o thedriven disk.

3. A transmission including a driving means, a driven disk, a shaftoperatively connected to the driving means and located radially relativeto the driven disk, a friction wheel threaded upon the shaft andfrictionally engaging the adjacent undersurface of the turntable nearthe periphery thereof.

As the motor 22 is operated, the friction pulley 25 drives the frictionwheel 3| and shaft 21, and through the spring 43 the friction wheel 36is rotated, driving the turntable at proper speed.

In the operation of the phonograph, as the pressure of the needle uponthe record, carried by the turntable, offers resistance to the rotationof the turntable, the spring 43 will be wound upon itself rotating themovable friction Wheel 36 upon the shaft in a direction whereby thescrew threads 39-40 cause the wheel 36 to move longitudinally on theshaft toward the center of the turntable, bringing the tire 31 of thewheel 36 into contact with the turntable at a point closer to the centerthereof.

side of the driven disk, stop means upon the shaft for limiting themovement of the friction Wheel in one direction, and a. torsion springconnected to the friction wheel and to the shaft for urging the frictionwheel toward the stop means, so that the friction wheel is movedradially relative to the driven disk by variations in drag to compensatefor resultant variations in speed of the driven disk.

4. A transmission including a driving means, a driven disk, a shaftoperatively connected to the driving means and having a spiral groovetherein, said shaft being located radially relative to the driven disk,a friction wheel longitudinally movable upon the shaft and having aninternal, spiral rib received in said spiral groove, said friction wheelfrictionally engaging the adjacent side of the driven disk, and atorsion spring connected to the friction wheel and to the shaft formoving the friction wheel radially upon the driven disk to compensatefor variations in` drag and resultant speed changes of the driven disk.

EMMOR V. SCHNEIDER.

